Mixture of borates containing active oxygen.



No Drawing. Original application OFFICE.

FRIEDRICH LUDWIG SCHMIDT, OF CHARLOTTENBURG, GERMANY, ASSIGNOR TO THE ROESSLER & HASSLACHER CHEMICAL COMPANY, A CORPORATION OF NEW YORK.

MIXTURE OF BORATES CONTAINING ACTIVE OXYGEN.

To all whom it may concern:

Be it known that I, FRIEDRICH LUDWIG SCHMIDT, a citizen of the Gjennan Empire, residing in Charlottenb urg, Germany, have invented certain new and useful Improvements in Mixtures of Borates Containing Active Oxygen, of which the following is a specification.

Sodium perborate possesses the property of giving ofl its oxygen rather rapidly-in water at a temperature as low as C. This is a disadvantage in the application of sodium'perborate as a bleaching agent, inasmuch as the washing and b eachi'ng process can only properly begin at a higher temperature, so that a large proportion of the oxy on will be driven off and its effect lost beigire the efficient temperature is attained. In view of this fact, the discovery that magnesium perborate evolves its "oxygen at a higher temperature represented an advance.

It is known that mixtures of sodium per borate and a magnesium salt in equivalent proportions can be employed for bleaching, instead of pure magnesium perborate. In this case the magnesium perborate is formed from the sodium perborate, and the magnesium salt by double decomposition. The proportions which are used in the lat ter process are such that the whole of the sodium perborate is decomposed by the magnesium salt. To this extent the latter process differs from that with magnesium perborate in the fact that the magnesium perborate is produced by the said double decomposition just before the bleaching occurs.

While the employment of magnesium perborate for bleaching purposes represents an advance as regards the bleaching effect, owing to the greater stability of the magnesium perborate under boiling, yet, on the other hand, its high price and some other shortcomings militate agianst its wide employment. 5 v

I'have found that itis possible to obtain the effect of greater resistance to boiling with the cheap sodium perborate and with Specification of Letters Patent.

other alkali metal perborates containing acf tive oxygen, by adding certain substances claimed in a separate application filed by Patented Sept. 28, 1915.

to the same. These substances include the salts of magnesium, and their base, magnesia itself.

The process so far as it extendsto the addition of magnesium, difi'ers from the above-mentioned process according to which sodium perborate is completely decomposed bylt equivalent proportions of magnesium sa It is not necessary to add to the alkali action of than equivalent proportions of magnesium salt was not to be foreseen,

for in the process the greater portion of the sodium perborate remains unalteredin A solution, and the natural assumption would therefore-be that this unaltered sodium pe'rborate would split off the oxygen as readilyas do ordinary solutions of sodium perborate. I

The process utilizing only small quantities of-magnesium salt-is of special advantage on account of its technical advantage over the process using either ready prepared magnesium perborateor freshly formed magnesium perborate. Both magnesium perborate and the magnesium borate into which the former becomes converted after the bleaching action are insoluble. There is therefore in the bleaching liquor a considerable quantity of such magnesium precipitate, which, owing to the large quan titg present, has a detrimental effect and is di cult to remove from the bleached goods. Bynsing smaller quantities of magnesium salt, less of this troublesome precipitate has to be dealt with, and the less the quantity The new mixtures above described are me, January 20th, 1910, under'Serial Num- I ber 540,044, of which this application is a division. p

I have further found that not only magnesium possesses the described action, but the same action is also possessed by the soluble compounds of zinc such as zinc chlorid, or its equivalent. It is Well known that zinc chlorid in solutions is readily ionized. The addition of one-fifteenth of a molecular proportion of chlorid of zinc is found to make the solution stable so that the percentage of oxygen remaining after heating is much greater than when the zinc chlorid is not present.

The stabilizing effect of the soluble com-- pounds of zincapplies not only to sodium i perborate, but also to the other borates con- Patent of the United States issued to me, October 24th, 1911, under No. 1,006,798.

The effect obtained also applies to mixtures of the borates containing active oxygen .With other substances having a similar action. The said stablizing substances may be added to the active borates and the mixture of bothv of them, ready for use, may be placed upon the market, or the procedure may be such that they are added just before use or during use..

It is not necessary that the salts or bases having an action in the described sense shall be of the ordinary kind; for example, the per-salts and peroxids of the same Will serve the purpose.

I claim:

A bleaching mixture, comprising a perborate and a soluble inorganic compound of zincpin less than an equivalent molecular proportion, and having a superior bleaching effect. 7

In testimony, that I claim the foregoing as my invention, '1 have signed my name in presence of two subscribing Witnesses. FRIEDRICH LUDWIG SCHMIDT. Witnesses:

WOLDEMAR HAUPT, HENRY HASPER. 

